[PATCH] panic: add TAINT_SOFTLOCKUP

Josh Hunt
2014-06-04T02:20:04Z

This taint flag will be set if the system has ever entered a softlockup
state. Similar to TAINT_WARN it is useful to know whether or not the system
has been in a softlockup state when debugging.

Signed-off-by: Josh Hunt <johunt@akamai.com>
---
Documentation/oops-tracing.txt | 2 ++
Documentation/sysctl/kernel.txt | 1 +
include/linux/kernel.h | 1 +
kernel/panic.c | 1 +
kernel/watchdog.c | 1 +
5 files changed, 6 insertions(+)

diff --git a/Documentation/oops-tracing.txt b/Documentation/oops-tracing.txt
index e315599..beefb9f 100644
--- a/Documentation/oops-tracing.txt
+++ b/Documentation/oops-tracing.txt
@@ -268,6 +268,8 @@ characters, each representing a particular tainted value.
14: 'E' if an unsigned module has been loaded in a kernel supporting
module signature.

+ 15: 'L' if a soft lockup has previously occurred on the system.
+
The primary reason for the 'Tainted: ' string is to tell kernel
debuggers if this is a clean kernel or if anything unusual has
occurred. Tainting is permanent: even if an offending module is
diff --git a/Documentation/sysctl/kernel.txt b/Documentation/sysctl/kernel.txt
index 9886c3d..8dfdf2f 100644
--- a/Documentation/sysctl/kernel.txt
+++ b/Documentation/sysctl/kernel.txt
@@ -788,6 +788,7 @@ can be ORed together:
4096 - An out-of-tree module has been loaded.
8192 - An unsigned module has been loaded in a kernel supporting module
signature.
+16384 - A soft lockup has previously occurred on the system.

==============================================================

diff --git a/include/linux/kernel.h b/include/linux/kernel.h
index 4c52907..eb7b074 100644
--- a/include/linux/kernel.h
+++ b/include/linux/kernel.h
@@ -470,6 +470,7 @@ extern enum system_states {
#define TAINT_FIRMWARE_WORKAROUND 11
#define TAINT_OOT_MODULE 12
#define TAINT_UNSIGNED_MODULE 13
+#define TAINT_SOFTLOCKUP 14

extern const char hex_asc[];
#define hex_asc_lo(x) hex_asc[((x) & 0x0f)]
diff --git a/kernel/panic.c b/kernel/panic.c
index d02fa9f..d68c5d8 100644
--- a/kernel/panic.c
+++ b/kernel/panic.c
@@ -212,6 +212,7 @@ static const struct tnt tnts[] = {
{ TAINT_FIRMWARE_WORKAROUND, 'I', ' ' },
{ TAINT_OOT_MODULE, 'O', ' ' },
{ TAINT_UNSIGNED_MODULE, 'E', ' ' },
+ { TAINT_SOFTLOCKUP, 'L', ' ' },
};

/**
diff --git a/kernel/watchdog.c b/kernel/watchdog.c
index 516203e..09ac67c 100644
--- a/kernel/watchdog.c
+++ b/kernel/watchdog.c
@@ -329,6 +329,7 @@ static enum hrtimer_restart watchdog_timer_fn(struct hrtimer *hrtimer)

if (softlockup_panic)
panic("softlockup: hung tasks");
+ add_taint(TAINT_SOFTLOCKUP, LOCKDEP_STILL_OK);
__this_cpu_write(soft_watchdog_warn, true);
} else
__this_cpu_write(soft_watchdog_warn, false);
--
1.7.9.5